Sewing machine work feed adjusting device



May 29, 1962 E. F. DUNN ET AL 3,036,535

SEWING MACHINE WORK FEED ADJUSTING DEVICE Filed July 28, 1959 INVENTORSEarl E Dunn Elmer Koszfa 2. V ATTORNEY WITNESS United States atent3,036,535 SEWING MACHINE WORK FEED ADJUSTING DEVICE Earl F. Dunn,Monroe, and Elmer Koszta, Fairfield,

Conn., assignors to The Singer Manufacturing Company, Elizabeth, N.J., acorporation of New Jersey Filed July 28, 1959, Ser. No. 830,018 1 Claim.(Cl. 112-210) This invention relates to sewing machines having workfeeding mechanisms capable of adjustment to vary the length of stitchesand, more particularly, to a device for at will positioning andmaintaining the work feeding mechanism at a selected stitch length.

It is an object of this invention to provide a novel stitch lengthadjusting device for a sewing machine with which a desired stitch lengthadjustment may be made easily and conveniently, and the adjusting devicelocked in selected position requiring only the use of one hand of amachine operator to accomplish both the adjusting and the locking.

Another object of this invention is to provide a clamping device forsecuring a stitch length adjusting member in a selected position inwhich the operation of the clamping device cannot influence the positionof adjustment of the stitch length adjusting device.

With the above and other objects and advantages in view, this inventionis described hereinbelow and illustrated in the accompanying drawings ofa preferred embodiment in which:

FIG. 1 represents a vertical transverse cross sectional view of thestandard portion of a conventional sewing machine, illustrating theregulating and adjusting devices for a conventional drop feed mechanismand having the present invention applied thereto,

FIG. 2 is an enlarged cross sectional view taken substantially alongline 2-2 of FIG. 1, and

FIG. 3 is a cross sectional view taken substantially along line 3-3 ofFIG. 2.

Illustrated in FIG. 1 is a conventional type sewing machine frameincluding a hollow standard 11 rising from a bed 12. Journaledlengthwise in a bracket arm (not shown) and passing through the upperpart of the standard is a main drive shaft 13 which serves in the usualmanner to actuate the stitch forming instrumentalities of the sewingmachine.

The mechanism disclosed in the sewing machine frame of FIG. 1 is thatwhich generates and controls the feed advance and return motions of afour-motion or drop feed mechanism. By four motion or drop feed is meantthat in which a feed dog rises into engagement with the work, advancesin the direction of feed while raised, drops out of engagement with thework beneath the level of the bed 12 or a throat plate thereon (notshown), and returns while so dropped.

Indicated at 14 in FIG. 1 is a feed advance and return rock shaftjournaled beneath the bed 12. A rock arm 15 fast on the feed advance andreturn rock shaft is pivoted to a pitman 16 which extends upwardlythrough the hollow standard and is formed with bifurcations 17 embracinga slide block 18 which is journaled on an eccentric 19 fast on the maindrive shaft 18.

Pivoted to the pitman 16 on a pin 20 is an anchor link 21 which isanchored on a pivot pin 22 carried on an adjusting block 23 fulcrumed onthe pivot pin 24 in a bearing lug 25 formed inside the hollow standard.

Pivotally carried on a pin 26 secured in the adjusting block 23 is oneextremity of a connecting link 27 pivoted. at its other extremity bymeans of a pin 28 to feed adjusting lever 29. The feed adjusting leveris fulcrumed on a pin 30 secured between spaced abutments 3 1 formed atthe rear of the hollow standard and extends through a vertical slot 32formed in the front wall of the hollow standard, outwardly of which thefeed adjusting lever 29 is formed with a hand grip portion 33.

By means of the control lever 29, the connecting link 27, and the block23, the sewing machine operator may at will effect changes in theposition of the anchor link 21 with respect to the pitman 16, wherebythe extent of oscillatory motion imparted to the feed advance and returnrock shaft 14 may be regulated and the direction of oscillation may bechanged to reverse the direction of feed of the work being stitched.Thus, when the anchor link 21 is shifted into substantial alignment withthe pitman, no appreciable motion will be imparted to the feed rockshaft 14 and no work feeding will occur. When the lever 29 is raised,the pivot pin 22 joining the anchor link 21 to the adjusting block 23will be shifted to the left of the pitman 16, as viewed in FIG. 1, andmotion will be imparted to the feed rock shaft 14 to effect work feedingmovements in the normal forward direction. Similarly, when the lever 29is depressed, the pivot pin 22 will be shifted to the opposite side ofthe pitman 16 and the work feeding movements will be reversed.

Threaded into the front wall of the sewing machine standard 1 1 is afeed length adjusting screw 4! formed with a rounded extremity 41extending between angularly arranged abutment surfaces 42 and 43 formedon the adjusting block 23. The surfaces 42 and 43 are arranged on theblock 23 such that when the angle defined therebetween is bisected bythe axis of the adjusting screw 48, the feed regulating anchor link 21will be disposed in a position corresponding to that of zero stitchlength. In any position of adjustment, the adjusting screw 40 will limitblock 23 to an equal amount on either side of the Zero stitch lengthposition and, therefore, the maximum stitch length at any setting willbe the same on both the forward and reverse directions of feed.

The feed regulating lever 29, being carried on a fulcrum pin 30 isconstrained such that all points on the lever move in fixed parallelplanes perpendicular to the axis of the fulcrum pin 30. A spring 45biases the feed adjusting lever 29 into raised position determined bythe abutment surfaces 42 and the adjusting screw 40, as illustrated inFIG. 1, which corresponds to the maximum stitch length in the forwarddirection of feed. The operator, by simply depressing the hand grip 33until the abutment surface 43 engages the end 41 of the adjusting screw,can automatically set the mechanism in position to feed the work in thereverse direction and with the same stitch length.

It is desirable with feed regulating mechanisms such as illustrated inthe drawings to provide a means for selecting one particular setting ofthe adjusting lever 29, and for locking the mechanism in the particularsetting selected. For this purpose, the slot 32 in the sewing machinestandard is provided with an escutcheon plate 5%) secured in place byscrews 51 and formed with a slot 52 opening into the machine standardslot 32. The escutcheon plate is also provided with a side edge 53disposed in a plane substantially perpendicular to the axis of thefulcrum pin 30, i.e., parallel to the fixed planes in which theadjusting lever is constrained to move. A pointer 54 secured by screws55 atop of the adjusting lever 29 is preferably resilient and urgedupwardly by a screw 56 threaded into the adjusting lever such that thepointer may be adjusted to register accurately with indicia (not shown)on the escutcheon plate to represent the length of stitch correspondingto the position of the adjusting lever 29.

Loosely fastened to the adjusting arm 29 on a fastening screw 60 beneaththe hand grip 33 is a clamp arm 61 formed with an arched finger 62extending over and snuggly embracing a circular flange 63 formed on aclamp screw 64 threaded in the adjusting arm 29. The clamp arm is formedat the free extremity with an offset clamping finger 65 disposedadjoining the side edge 53 of the escutcheon plate.

The clamp finger 65 is, therefore, carried not only into clampedengagement with the side edge 53 of the escutcheon plate 50 but also outof engagement therewith by the fiange 63 of the clamp screw whichcarries the arched finger 62 formed thereon.

The clamp screw 64 is disposed preferably between the hand grip portion33 of the feed adjusting and machine standard and is thus convenientlyaccessible for tightening or loosening with one hand without loss ofcontrol of the position of the adjusting lever. With the palm of thehand on the hand grip 33, the thumb and fingers of the hand are free andavailable for tightening and loosening the screw.

The clamping action of the clamp finger 65 against the side edge 52 ofthe escutcheon plate occurs in a direction substantially perpendicularto the planes of motion of the feed adjusting lever. The action of theclamp finger 65 in gripping the side edge 52 of the escutcheon will,therefore, not exert any forces tending to shift the adjusting arm 29either up or down. The external shape of the escutcheon plate ispreferably arcuate to conform to the are described by the pointer 54,however, the shape of the escutcheon plate is of little consequence inthis respect and may vary considerably from the shape of the path ofmotion of the pointer without having any efiect upon the accuracy withwhich the adjusting arm 29 can be clamped in place.

The attribute of the present invention to permit the stitch lengthadjusting arm to be clamped easily and accurately in selected positionis particularly advantageous in selecting small stitch lengths on azigzag sewing machine where the appearance of the seam is influenced toa large extent by the spacing of successive stitches.

Having thus set forth the nature of this invention, what is claimedherein is:

In a work feeding mechanism for a sewing machine having a casing, 21shiftable feed regulating lever pivotally supported for oscillatorymovement about an axis fixed in the sewing machine casing and protrudingoutwardly through a clearance slot in the casing, a substantially fiathorizontal hand grip portion formed at the free extremity of said feedregulating lever protruding out of the machine casing, means for lockingsaid feed regulating lever in selected position of adjustment comprisingan escutcheon plate secured on said sewing machine casing over saidclearance slot, an abutment portion of uniform width on said escutcheonplate at one side of said clearance slot, a clamp arm loosely secured onsaid feed regulating lever, clamp screw means operatively engaging andclamp arm for shifting said clamp arm toward and away from said feedregulating lever in a direction parallel to the pivotal axis of saidfeed regulating lever, means threadedly engaging said clamp screw onsaid feed regulating lever between the hand grip portion of said feedregulating lever and the machine casing so as to be immediatelyengageable by the operation fingers when the palm of the operators handtouches the hand grip portion, and a clamp finger extending from saidclamp arm and on the opposite side of said escutcheon abutment portionfrom said feed regulating lever.

References Cited in the file of this patent UNITED STATES PATENTS373,391 Daggett Nov. 15, 1887 1,951,922 Cantrell Mar. 20, 1934 2,723,635Matuzas Nov. 15, 1955 2,725,023 Ayres Nov. 29, 1955 2,877,727 GraesserMar. 17, 1959 FOREIGN PATENTS 358,192 France Jan. 3, 1906

